How is this water suspended in mid-air?
It’s an effect created by the frame rate and shutter speed of the Canon 5D Mark II used to capture it, along with the vibration of the speaker. The video creator describes his setup as follows:
…you’re actually seeing 25 different drops every second, the uniformity of the waveform being played through the speaker is vibrating the pipe in a uniform way, so the drops exit the pipe uniformly, the frame rate of the camera is synced with the speaker so the drops appear static, the short shutter speed means the drops appear sharp and frozen in mid air, a longer shutter speed would show motion blur. To see this with the naked eye, without a camera, you need a strobe light.
…basically the bit where I adjust the knob is me turning up the volume on my amp. This affects how far the tube vibrates back and forth, in this case it causes the tube to kind of vibrate in a circle, making a broken spiral of water. The frequency of the speaker is controlled from a test oscillator played from a laptop.